Question

Boat goes 5m/s and the river current is moving at 3m/s. At what angle must this rower point upstream to be able to land directly across the river. The answer in NOT 30degrees.

Answer 1

Answer:

Angle made boat = 120° from  the direction of river stream

Explanation:

Velocity of boat  = Vb = 5 m/s

Velocity of river = 3 m/s

velocity of boat wrt river Vbr = Vb - Vr = 5 - 3 = 2 m/s

Let θ be the angle made by the boat wrt vertical

For shortest path

tanθ = Vr/Vb = 3/5

    θ = tan⁻¹(3/5) = 30.96°

Angle made by boat with direction of river stream = 90° + 30.96°

                                                                                    = 120.96°